Astronomy 2021A/B Lecture Notes - Lecture 12: Rare Earth Hypothesis, Encephalization Quotient, Cambrian Explosion
9 Dec 2016
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Document Summary
The search for intelligence means searching for communications. Equation for the number of civilizations in our galaxy from which we could potentially get a signal: not cavemen, or even cowboys, doesn"t give a definitive answer: just lays out the important factors, the odds of each. The drake equations is: number of civilizations = nhp * flife * fciv * fnow, nhp: the number of habitable planets in the galaxy. Prerequisite for having life or a civilization, so it comes first: flife: fraction of habitable planets that have life. If all habitable worlds have life: flife = 1. If 1 in a million have life flife = 1/1,000,000. So nhp x flife is the number of habitable worlds with life. Life arose quickly so maybe its easy in which flife would be 1. Rare earth hypothesis says its close to zero: fciv: fraction of worlds with life where a civilization capable of interstellar communication has arisen, at any time at all.
